Photographic emulsion



' of color photographic emulsions.

affected by the color forming development coming a light-sensitive layer having a color formand a sensitizer for green, which is unaffected the sensitivity in the green region of the spectrum 'trimethine cyanines'which contain at either or Maths. 8, 1942 PHOTOGRAPHIC EMULSION Gustav Wilmanns, Wolten, Krels Bitteri'eld, and

Oskar Riester, Dessau-Zlebigh-Germany, assigns, by mesne assignments, to General An iline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application June 21, 1939, Serial No. 280,352. In Germany June 23, 1938 s claims. (or. 95-7) Our present'invention relates to the sensitizing The dyestufls used in the invention have the following general formula:

It is known that a large number of the best known sensitizers are not suited for sensitizing action is considerably reduced or completely disappears in the presence of the dyestuif components.

It is therefore an object of the present inven- 10 tion to provide sensitizing "dyes, which are uno Y- .silver halide emulsions containing color forming 5 I I I development components since their sensitizing O N I x..

wherein Y is oxygen, sulfur or selenium, X is any desired acid radical, for, example Cl, Br,

A further object resides in the provision of a C104 CHsso" or cal-Iss" I m h a photographic light-sensitive element comprislo z'm fm ggg zr Moreover in the unsymmetrical dyestuffs the benzthiazole or benzselenazole ring can have one or more substituents in the 4-, 5- or 6.-position, for example an alkyl radical with 1-5 carbon atoms, an alkoxy radical or a halogen. If Y is oxygen the benzoxazole ring must' contain 6- ph'enyl as a substituent. v

The invention is illustrated by-the following examples:

ponents.

ing development component for purple or blue by the presence of the color former in the layer.

Further objects will appear from the detailed description following hereinafter.

This invention is based on the observation that of silver halide emulsions containing color-form ers can be. increased by using as sensitlzers 5 Example 1 each end of the polymethine chain a benzoxazole ring substitutedrin the 6-positionby phenyl. IByv from 2-methyl-6-phenylbenzoxazole diethyl sulthe 6-position we understand the para-position phate and orthoacetic acid ethyl ester in pyridine, to the oxygen atom of the benzoxazolevring. having the formula I an.

- The shsitizmg dye'stufi can be used alone or 40 is added to a silver halide emulsion which conwith previously described sensitizing dyestuffs.

The sensitizing is carried out in the usual mansensimtmmaximum 545 ner, a dyestufi component for purple being added Example 2 to the emulsion at a convenient stage of the preparation of the latter. 1012131 asymmetrical trimethine cyanine of the 0 Cam 0 :'--0H=0CH=J:

N $3: (5H) CHaSOt The symmetrical trimethine cyanine produced tains a dyestufl component for purple or yellow. 1

which is precipitated as the iodide. This dyeis obtained by condensing in pyridine 2-methyl- G-phenyl-benzoxazole dimethyl sulphate with u.-

phenylimino-a-methylthiopropane of the followins formula The dyestuff is added to a silver halide emulsion containing a dyestufrcomponent for blue :or

purple.

Sensitization maximum: 550 m Example 3 From the intermediate product obtained as described in British Patent No.4l2,309 and having the following formula there is obtained by condensation with 2-4z6- trimethylbenzthiazole ethyl iodide an unsymmetrical trimethine cyanine having. the following formula:

This dyestufi is added to a silver halide emulsion which contains a. color-former for purple.

Sensitization maximum: aboutj585 m Example 4 The intermediate product used in Example 3 but with methyl instead of ethyl in the chain,

is condensed with 2:5:6-trimethylbenzthiazole stuff is added to a silver halide emulsion which contains a color-former for purple.-

The dyestufi component for purple in the silver halide emulsions in Examples 1,v 2 and 3 is 1- phenyl-3'-carboxylic acid-3:4-abietyl-aminophenyI-B-pyra'zolone; in Example 4 it is 4:4- diphenylcarboyl-3-(4"- aminophenyl) 1 -(para 3'-benzthiazole-2'-phenyl)e5-pyrazolone; and in Example 5 it is' the condensation product of cholatrienic acid chloride and 1:3'-amino-5'- sulphophenyl-3-methy1-5-pyrazolone.

We claim: r I 1. A photographic material comprising a lightsensitive silver-halide emulsion layer containing a purple color forming development component derived from a S-pyrazolone and a sensitizer consisting of a dyestufi of the following general formula:

wherein Y is a member .of the group consisting'of oxygen, sulfur and selenium, X is an anion and A is a member of the class consisting of benzo, alkyl benzo, phenyl benzo, alkoxy benzo and halogen benzo, the substituents onthe benzo group being in a position of the class consisting of theI4-, 5- and 6-positions, A always being phenylbenzo with the phenyl group in fi-position. when Y is oxygen.

2. A photographic material comprising a light-sensitive silver-halide emulsion layer which contains a purple color-forming development component derived, from a 5-pyrazo1one and as toluene ethyl sulphate to produce the dyestuff having the following formula:

,CHi

This dyestufi is added to a silver halide emulsion which contains a color-former for purple.

Sensitization maximum: about 565 m Example 5 The intermediate product used in Example 4 is condensed with Z-methylbenzselenazole diethyl sulphate to produce a dyestuff having the following formula:

a sensitizer .a dyestufl 'of the following general formula: v

wherein Y is a member of the group consisting of oxygen,

sulfur and selenium a X is an anion R1 and Rzare alkyl radicals, and

R3 is phenyl.

3. A photographic material comprising a lightsensitive silver halide emulsion layer which contains a purple color forming development component derived from a S-pyrazolone and as a sensitizer a dyestufi of the following general formula:

GUSTAV WILMANNS. OSKAR RIESTER.

Certificate of Correction Patent No. 2,295,276. a GUSTAV WILMAN N S ET September 8, 1942 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column,.lines 5 t0 8 inclusive, strike out the formula and insert instead and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofl ice.

Signed and sealed this 16th day of March, D. 1943.

" HENRYVAN ARSDALE, Acting 0onum'erariomar of Patents. 

